Ecological relationships between bacteria are important when considering variation in bacterial communities in humans, with such variation playing an important role in both health and disease. Using high-throughput sequence data of the 16S rRNA marker-gene, we analysed the prevalence of taxa in the airways of a number of health- and disease-associated cohorts and determined the main drivers of community variance and bacterial co-occurrence. A number of facultative and obligately anaerobic bacterial taxa are commonly associated with the upper airways, forming the main "core" microbiota, e.g. Streptococcus spp., Veillonella spp., Prevotella spp., Granulicatella spp. and Fusobacterium spp. Opportunistic pathogenic bacteria associated with chronic airways disease, such as Pseudomonas spp. (Pseudomonas aeruginosa), Burkholderia spp. (Burkholderia cepacia complex) and Haemophilus spp. (Haemophilus influenzae) demonstrated poor correlation with other members of their respective communities (ρ<0.5; p>0.005), indicating probable independent acquisition and colonisation. Furthermore, our findings suggest that intra-genus variation between health and disease may affect community assemblies. Improved understanding of how bacteria assemble in time and space during health and disease will enable the future development of tailored treatment according to the patient's own signature microbiota, potentially providing benefit to patients suffering from airway diseases characterised by chronic infection.